Interest in using marijuana to treat the symptoms of Parkinson’s disease has grown in recent years as 33 states and the District of Columbia have legalized it for medical use.
Although the federal government has not approved medical marijuana itself, the U.S. Food and Drug Administration (FDA) has authorized some therapies that use specific marijuana components.
the FDA has given it's okay for the THC-based drugs Marinol (dronabinol) and Cesamet (nabilone) to ease nausea during cancer treatment and stimulate appetite. THC, or tetrahydrocannabinol, is an active component in cannabis known to effect mood, behavior, and thinking.
Known as cannabinoids, CBD and THC act on cannabinoid receptors in the brain that regulate body functions and have been shown to play a role in Parkinson’s, according to an article published in 2017 in the journal Cannibis and Cannabinoid Research. Still, the federal government has yet sign off on any marijuana-based formulas that might help the symptoms of this neurological disorder.
As more states have signed up to legalize medical cannabis, patients have increasingly been exploring it as a way to treat their Parkinson’s symptoms. Some who may have found standard drugs to be insufficient turn to marijuana to help sleep, lower anxiety, or reduce tremors, according to the Parkinson's Foundation.
Robert Duarte, MD, director of Northwell Health's Pain Center in Great Neck, New York, treats several patients with Parkinson’s who have tried medical cannabis to alleviate pain-related problems.
“I have also seen it work on insomnia and anxiety,” he says. “If you’re sleeping better and have less anxiety, there is definitely a relationship between that and improving your tremor.”
But marijuana doesn’t work for everyone, and doctors have to rely on educated guesswork to recommend cannabis-based products.
“The problem is there are no standards for dosing or manufacturing different forms of medical cannabis,” says James Beck, PhD, chief scientific officer with the Parkinson’s Foundation. “Some people equate access to efficacy. Just because you can gain access to medical marijuana through legalization changes in different states doesn’t mean that it’s effective for a disease.”
Rebecca Gilbert, MD, PhD, chief scientific officer for the American Parkinson Disease Association in New York City, knows many Parkinson’s patients who have experimented with medical cannabis and had mixed results.
“It’s not a panacea. I have many patients who have tried it, and said it did not help sleep, tremors, or cramping,” she says. “But there is a subset of patients who find it’s useful, and we need to better understand who it’s useful for.”
The decision to use medical marijuana comes down to an individual choice based on weighing the pros and cons.
The Parkinson’s Foundation reports that some research has found cannabis to be neuroprotective, offering potential guard against damaging neurons. The cannabinoids may protect brain cells through antioxidant and anti-inflammatory properties, notes the Michael J. Fox Foundation.
In addition to possible sleep, anxiety, and tremor benefits, patients may find that it relaxes muscles and makes movement easier. One of the symptoms of Parkinson’s is rigidity from a tightening of the muscles. It may also help with loss of appetite.
Because dosing can be difficult, potency of the cannabis can pose risks. Parkinson’s patients can have trouble with cognition, and strong marijuana can cause problems with learning, memory, and thinking. If a person gets too high, he or she can feel overanxious and paranoid, and have difficulty functioning at all. If the product is too strong, the user may experience hallucinations or delusions, according to Dr. Beck.
Dr. Duarte advises that you don’t want to give a THC component to anyone who is at risk of psychosis.
Sustained marijuana use may raise blood pressure, according to a study published in August 2017 in the Journal of Hypertension, and Beck cautions that the product may also cause blood pressure to drop dangerously low.
“Low blood pressure can lead to a fall, which can be disastrous. It can lead to head injuries, a broken hip, or even death,” he says.
Dr. Gilbert suggests that patients interested in trying medical marijuana consult with a physician and review their response with the doctor.
Some patients who might find benefits from marijuana may still feel a stigma surrounding the product, noted an article published in November 2018 in the National Pain Report. It can be difficult to accept the idea that the once-illegal product is now legal and accepted in many states. Some family and friends may still judge users negatively.
“Some people are taught you should never do marijuana — it hurts people and makes you dopey,” says Duarte.
On the other hand, Gilbert believes many users embrace the product as a natural, do-it-yourself remedy. She expects that more scientific study would only improve its respectability.
So far, studies have been minimal and no trial has definitively found that it works to improve the disease.
“There are lot of combinations out there of THC and CBD, but not a single one has been fully tested for any symptom of Parkinson’s,” says Gilbert.
As medical marijuana has become more accepted, however, the research tide may be turning.
In fiscal year 2017, the National Institutes of Health supported 330 projects totaling almost $140 million on cannabinoid research. Within this investment, 70 projects ($36 million) examined therapeutic properties of cannabinoids, and 26 projects ($15 million) focused on CBD.
The Parkinson’s Foundation lists a handful of investigations that have evaluated the effects of cannabinoids on the disorder. In a study published in March 2015 in the journal Movement Disorders, scientists analyzed the therapeutic potential of cannabinoids for movement disorders but didn’t find any conclusive proof that marijuana helped. That investigation summarized several other studies on the topic.
A report published in January 2017 by the National Academies of Science, Engineering, and Medicine reviewed 10,000 scientific abstracts regarding marijuana’s effect on health, and concluded there was not enough evidence to support using medical marijuana for Parkinson’s.
“Medical cannabis is here and it is going to be utilized, but we need more research to provide guidelines,” says Beck. “Hopefully we’ll get to a point where we will know how to utilize marijuana in a safe manner.”